Changes in the plasma concentrations of free and conjugated oestrogens in heifers after treatment to induce superovulation and the relationship with number of ovulations

Abstract

Oestradiol-17 beta and conjugated oestrone, oestradiol-17 beta and oestradiol-17 alpha were measured in peripheral plasma of heifers treated with PMSG/PGF-2 alpha to induce superovulation. Changes in the concentrations of each hormone were synchronous, the highest level being near oestrus. For a given number of ovulations the hormone with the highest concentration was total oestradiol-17 alpha, then came total oestrone, total oestradiol-17 beta and oestradiol-17 beta. For each oestrogen, the maximum preovulatory concentration measured was significantly correlated with the number of ovulations; the regression line for total oestradiol-17 alpha was twice as steep as that for oestradiol-17 beta. It is concluded that in animals treated to induce superovulation assay of total oestradiol-17 alpha gives a better induction of the number of follicles induced to ovulate than does the more conventional assay of oestradiol-17 beta.

Influence of maternal environment on the number of transferable embryos obtained in response to superovulatory FSH treatments in ewes

“…The relationship between the number of follicles 2-4 mm in diameter and the oestradiol levels from 12 h before to 36 h after oestrus detection also confirms that the administration of high doses of exogenous gonadotrophins induces the growth of these follicles until the preovulatory stages. Thereafter, the relationship found between the oestradiol levels around estrus and the number of corpora lutea and total and viable embryos confirmed the results already published for cattle [20][21][22], indicating that oestradiol concentration around the onset of oestrus behavior can be considered as an indicator of the population of healthy preovulatory follicles, as in cattle [8].…”

“…The analysis of hormonal assays showed that plasma oestradiol (E2) levels, depicted in Figure 1, increased from the first FSH injection (4.0 ±0.7 pg·mL ) to the onset of 22 A. González-Bulnes et al ). The E2 levels at -12 h, 0 h, 12 h, 24 h and 36 h from the detection of oestrus behavior were positively correlated with the total number of follicles 2-4 mm in diameter at the first FSH dose (P < 0.05, r = 0.824), and mainly with the number of 3-4 mm follicles (P < 0.005, r = 0.900).…”

“…Viability of the embryos from the oviduct was determined by assessing its development to expanding or hatching blastocysts in co-culture with the oviduct epithelial cell monolayer [16]. The coculture of embryos from oviduct recoveries with oviduct epithelial cell was chosen to avoid the block to in vitro embryo development in a conditioned medium described at the 8-16 cell stage [17], when the control of the embryo development changes from the maternal genome to the embryonic genome [18]. In brief, preparation of the oviduct cells was performed from sheep oviducts in the luteal phase of the oestrous cycle.…”

“…The effects of follicular status and endocrine patterns were examined by assessing the follicular population and plasma progesterone and oestradiol levels in a group of ewes in which embryos were thereafter recovered from the uterus. The influence of a developmental competence of the embryos and the effects 18 A. González-Bulnes et al…”

Comparable vasorelaxant effects of 17α- and 17β-oestradiol on rat mesenteric resistance arteries: an action independent of the oestrogen receptor

“…To test this hypothesis, we examined the vasorelaxant effects of 17α-oestradiol (17αE # , a naturally occurring isomer of 17βE # ), which has very low affinity at the oestrogen receptor [17,18]. 17βE # is the most abundant circulating oestrogen in mammals, including humans, with particularly high levels at the time of the pre-ovulatory peak, while 17αE # is present only at very low levels [19][20][21][22][23]. We have compared the effects of 17αE # and 17βE # on depolarization-and agonist-induced contraction of resistance rat mesentery arteries, and investigated the dependence of these effects on nitric oxide generated by the endothelium and on intra-and extra-cellular calcium.…”